Triangle-loop antenna

ABSTRACT

An antenna for receiving three widely separated frequency bands; the antenna beginning with a triangular tapered section fed by a coaxial line and continuing with several loops terminated in the center at ground.

United States Patent [21] Appl No. [22] Filed [45] Patented [73]Assignee [54] TRIANGLE-LOOP ANTENNA 8 Claims, 5 Drawing Figs.

[52] US. Cl 343/848, 343/895, 343/908 [5|] lnt.Cl H01g 1/36, H01 g 1/48150] Field of Search. r ,7 343/741-4, 728, 848. 82983 1 895 [56]References Cited UNlTED STATES PATENTS 3.015.101 12/1961 Turner etal.343/848 Primary ExaminerHerman Karl Saalbach Assistant Examiner-MarvinNussbaum Attorneys-R. S. Sciascia and J. M. St.Amand ABSTRACT: Anantenna for receiving three widely separated frequency bands; theantenna beginning with a triangular tapered section fed by a coaxialline and continuing with several loops terminated in the center atground.

TRIANGLE-LOOP ANTENNA The invention herein described may be manufacturedand used by or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

It is an object of this invention to provide an antenna to be used totransmit or receive telemetry signals, for example, at three widelyseparated bands of frequencies. It is an object, for example, to providean antenna which will simultaneously receive electromagnetic energy inthe 1435-1535 MHz. band, in the 2200-2290 MHz. band and in a 4 me.increment of 220-260 MHz. band. There are no existing small antennasthat will accomplish this reception in three widely separated frequencybands. The old method required using two or three different antennas toaccomplish the same job, and also entails severe antenna mountingproblems. The present device is a multifrequency antenna whichincorporates characteristics of both a triangular antenna and anunbalanced loop antenna, but requires only one feed point.

Other objects and many of the attendant advantages of this inventionwill become readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a front plan view of the antenna.

FIG. 2 shows a rear view of the antenna of FIG. ll.

FIG. 3 is cross-sectional view along line 3-3 of FIG. 1.

FIG. 4 is a cross-sectional view of the antenna along line 41, of FIG.1.

FIG. 5 shows an example of antenna dimensions for specific frequenciesmentioned.

Referring to the drawings, like numerals refer to like pa ts in each ofthe figures. The drawings show the antenna is fed from a coaxial lineconnector 11 through a triangular tapered section 12 and through severalloops 14 of transmission line to point 17 where it is connected toground.

The antenna assembly 10, in the example shown in the drawings, is formedby the stripline method on a sheet of dielectric material 20, which inturn is fastened to a baseplate 22 by suitable means such as clips 24and 25 or the like and central conductor 26 of the coaxial lineconnector 11 (i.e. input-output terminal). Point 17 is connected toground via conductor 30, clip 25 and the baseplate. The triangulartapered section 12 and loop section 14 are made of copper or othersuitable metal.

At the two higher frequency bands (i.e. 1435-1535 MHz band and 2200-2290MHz band) given by way of example, most of the radiation emanates fromthe triangular section 12 of the antenna. To keep the triangular section12 from interacting with the loop section 14 at the higher frequencies,the loop section is spaced slightly apart from the triangular section at32. This separation 32 tends to improve the VSWR at higher frequencies.Other parameters that effect the VSWR at the higher frequency bands arethe height of the feed point 34, the height of the loop section 14 aboveground baseplate 22 and the angle (i.e. in example shown) of thetriangle section 112. Decreasing the height of the loop above groundimproves the VSWR (i.e. voltage standing wave ratio) at the higherfrequency bands. A height of 0.070 inch to 0.100 inch appear to give thebest VSWR. An angle of 15 with respect to ground for the triangularsection appears to give the best VSWR. The radiation pattern at thehigher frequency bands is nearly omnidirectional in the horizontal planewith approximately +1.5 db. perturbation. At the lower frequencies, theantenna is essentially an unbalance multiploop antenna. The

low frequency characteristics of the antenna are governed by thedistributed capacitance and inductance of both the loop section 14 andthe triangular section 12. The inductance and capacitance vary as (l)the width of the antenna copper, (2) the width of the loop spacing, (3)the length of the antenna copper strip and (4) the height of the loopabove the ground lane.

p Tuning of the antenna is accomplished by varying the overall length ofthe transmission line. Fine tuning is accomplished by shorting along themiddle spacing of the loop section 14. Referring to FIG. 11, one notesthat in the tuning section" the copper is extended into the middlespacing (essentially shorting the loop) at 38 increasing the resonantfrequency; copper is removed form the middle section for decreasing theresonant frequency. The radiation pattern of the antenna at the lowerfrequencies is very omnidirectional.

Only one antenna is required for transmitting energy over three widelyspaced frequency bands simultaneously, whereas in the old method two orthree antennas are required. The use of stripline also lowers the costof constructing the antenna.

What I claim is:

l. A multifrequency antenna for receiving three widely separatedfrequency bands, comprising:

a. a triangular tapered section,

b. an unbalanced loop section,

. c. said triangular tapered section connected to said loop section atthe narrowest portion of said tapered section,

- d. said loop section comprised of a plurality of loops terminatjng inthe center with a ground connection,

. e. said antenna being fed through a feed point on said triangulartapered section,

f. tuning of said antenna being accomplished by varying the overalldistance along the length of said tapered and loop sections, fine tuningbeing accomplished by shorting the spacing at the center of said loopsection.

2. An antenna as in claim 1 wherein said triangular tapered section isspaced slightly apart from said loop section, except where the twosections are connected, to prevent interaction at higher frequencies andimprove the voltage standing wave ratio.

.3. An antenna as in claim 1 wherein said triangular tapered section andloop section are constructed of thin sheet metal in the same plane.

4. An antenna as in claim 3 mounted on a flat sheet of dielectricmaterial. 7

5. An antenna as in claim 4 mounted perpendicular to a baseplate actingas ground and fed via a coaxial connector whose center conductor isconnected to said feed point on said triangular tapered section.

6. An antenna as in claim 5 wherein the voltage standing wave ratio athigher frequencies can be adjusted by varying the height of thetriangular tapered section and thus said feed point above the groundbaseplate, and the height of said loop section above the groundbaseplate.

7. An antenna as in claim 5 wherein low frequency characteristics ofsaid antenna being governed by the distributed capacitance andinductance of both said triangular tapered section and said loopsection, said distributed capacitance and inductance varying as thewidth of the antenna metal, the width of said loop spacing, the distancealong the length of the triangular tapered section and loop section fromfeed point to ground connection, and the height of said loop sectionabove ground baseplate.

8. An antenna as in claim 1 wherein the radiation pattern at the higherfrequency bands is substantially omnidirectional in the horizontal platewith +1.5 db. perturbation.

1. A multifrequency antenna for receiving three widely separatedfrequency bands, comprising: a. a triangular tapered section, b. anunbalanced loop section, c. said triangular tapered section connected tosaid loop section at the narrowest portion of said tapered section, d.said loop section comprised of a plurality of loops terminating in thecenter with a ground connection, e. said antenna being fed through afeed point on said triangular tapered section, f. tuning of said antennabeing accomplished by varying the overall distance along the length ofsaid tapered and loop sections, fine tuning being accomplished byshorting the spacing at the center of said loop section.
 2. An antennaas in claim 1 wherein said triangular tapered section is spaced slightlyapart from said loop section, except where the two sections areconnected, to prevent interaction at higher frequencies and improve thevoltage standing wave ratio.
 3. An antenna as in claim 1 wherein saidtriangular tapered section and loop section are constructed of thinsheet metal in the same plane.
 4. An antenna as in claim 3 mounted on aflat sheet of dielectric material.
 5. An antenna as in claim 4 mountedperpendicular to a baseplate acting as ground and fed via a coaxialconnector whose center conductor is connected to said feed point on saidtriangular tapered section.
 6. An antenna as in claim 5 wherein thevoltage standing wave ratio at higher frequencies can be adjusted byvarying the height of the triangular tapered section and thus said feedpoint above the ground baseplate, and the height of said loop sectionabove the ground baseplate.
 7. An antenna as in claim 5 wherein lowfrequency characteristics of said antenna being governed by thedistributed capacitance and inductance of both said triangular taperedsection and said loop section, said distributed capacitance andinductance varying as the width of the antenna metal, the width of saidloop spacing, the distance along the length of the triangular taperedsection and loop section from feed point to ground connection, and theheight of said loop section above ground baseplate.
 8. An antenna as inclaim 1 wherein the radiation pattern at the higher frequency bands issubstantially omnidirectional in the horizontal plate with +1.5 db.perturbation.